Camera Lens Parts: Autofocus Motor
One of the most universal camera lens parts is the autofocus motor. Every camera available on the market that has autofocus also has the motor as part of it's system, regardless if it's a point and shoot or a SLR.
How Autofocus Works
All autofocus systems work by having an AF sensor in the lens to determine the contrast in the image, so that it can separate objects. The system would then determine the subject by analyzing which object is most dominant in the frame. Distance is then determined between the camera and the subject. A signal through the control system is sent to the autofocus motor in the lens, which will set the focus to the correct setting.
Between 1960 and 1973, a company called Leitz patented a few autofocus and sensor systems, but this feature did not hit the market until 1977 with the point and shoot Konica C35 AF. Autofocus with the motor in the lens was first introduced to the market in 1981 with the Pentax ME F, an amateur SLR camera.
When autofocus was first developed for SLR cameras, some manufacturers kept the motor inside of the camera body rather than the lens. This trend has been slowly fading away, as companies like Canon and Nikon elected to manufacture motorized lenses instead.